With the development of science and technology and the improvement of quality of life, the performance of electronic products is continually improving. The enhancement of the performance of most electronic products is often accompanied by increased power consumption, and more heat is generated correspondingly. The electronic products cannot dissipate heat on their own but need to dissipate heat by adding a fan.
At present, cooling fans prevailing on the market are mainly fans that use a brushless direct-current motor. In the brushless direct-current motor, the position of a rotor determines which stator coil is to be driven, and the position of stator flux vector has to be synchronous with the position of rotor flux vector, such that the motor operates smoothly. To achieve such an objective, it is necessary to know the position of the rotor to determine a stator coil to be driven, lots of existing technologies can achieve such an objective, and the most commonly used technology is monitoring the position of the rotor by using a Hall Effect magnetic sensor. However, the Hall Effect sensor is great in size and weight, thus increasing the system cost and reducing the reliability. In addition, the sensor has poor temperature stability and high power consumption.
The Tunneling Magnetoresistive (TMR) magnetic sensor is a new magnetoresistive effect sensor that has been applied within the industry in recent years, which senses magnetic fields by using the tunnel magnetoresistive effect of magnetic multi-layer film materials, and has a smaller size, lower power consumption and a broader working range relative to the Hall Effect magnetic sensor. More importantly, compared with the traditional Hall sensor, the TMR sensor has an absolute predominance in terms of temperature stability and is more suitable for applications in environments with greater temperature changes. In a system with obvious heat generation, the range of changes in temperature of an environment where a fan control chip is located is broad, and the TMR sensor is more applicable thereto.